A major new area of interest that has emerged in recent years involves the question of whether systematic training in meditation may be associated with actual structural changes in the brain, and in the past several years, a sufficient body of evidence has accumulated to strongly suggest that such changes do in fact occur.
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Articles in This Issue
The Mind’s Own Physician: A Scientific Dialogue with the Dalai Lama on the Healing Power of Meditation
Ed. Note: This new book presents a groundbreaking dialogue that took place in 2005 between His Holiness the Dalai Lama and leading researchers and teachers from both Eastern and Western traditions. The event was sponsored by the Mind & Life Institute, a Colorado-based nonprofit that studies the intersection of science and meditation; this was its second such public meeting following a similar 2003 gathering at MIT. The excerpt below comes from the book’s Epilogue, which summarizes in scholarly fashion various clinical and basic studies on meditation published between 2006 and 2011.
The meeting upon which this book is based was held in November 2005. Since that time, and in part as a result of our meeting, research on meditation has flourished and is continuing its exponential rise. In this concluding section, we highlight what we consider to be some of the most important findings in basic and clinical research, the methodological challenges associated with this phase of the rigorous study of meditative practices, and questions that this new wave of research has ushered in. Our purpose is to highlight the most promising new findings in this emerging field and then discuss some of the challenges now facing it.
Cognitive and Attentional Function
In the past five years, considerable progress has been made in characterizing how various forms of meditation change basic cognitive and affective processes and their underlying neural circuits. For example, one study examined the impact of three months of intensive Vipassana practice in a retreat setting and reported on behavioral and neural changes associated with the “attentional blink,” in which heightened response to an initial stimulus prevents subjects from seeing a second stimulus.1 This effect may be due to a kind of excitement about or overinvestment in detecting the initial target that clouds the ability to see the subsequent target. Prior to the retreat, there were no differences between the meditators and age- and gender-matched control participants. However, after three months of practice, the meditators had less attentional blink, detecting the second target stimulus with significantly greater accuracy. These behavioral changes were accompanied by measurable changes in brain function. The three months of intensive practice apparently increased the meditators’ ability to allocate attention in a more balanced way, improving their performance on the task.
The Shamatha Project examined the impact of three months of intensive training in a concentration meditation practice known as shamatha, comparing performance on a sustained attention task between the meditators and a wait-list control group.2 The training resulted in significant improvements in perceptual sensitivity and vigilance. Improvements in visuospatial processing and working memory have also been reported for a meditation training that was much less intensive than the Shamatha Project, and in which participants were initially new to meditation. In one study, participants were randomly assigned to four sessions of either meditation training or listening to a recorded book.3 The meditation training was based upon the work of Alan Wallace, who was the meditation teacher in the Shamatha Project.4 Researchers reported that this meditation training led to significantly greater enhancements in visuospatial processing and working memory than the control group experienced.
An unusual study of selective improvements in cognitive function compared performance between similarly advanced practitioners of two different styles of Tibetan Buddhist meditation: deity yoga, which involves visualizing a complex and multicolored three-dimensional image of a Tibetan deity, and open presence meditation, which involves cultivating evenly distributed attention that is not directed to any particular object or experience.5 The effect of these very different forms of meditation on visuospatial processing was measured before and after a twenty-minute period of meditation practice. The deity yoga practice led to substantial improvements on both a mental rotation task and a visual memory task compared with the open presence meditation. These results indicate that a short period of practice is sufficient to induce changes that persist into a subsequent task period and selectively enhances tasks that depend upon visual information processing.
Alterations in Brain Function and Structure
It is possible that future studies will show that mindfulness training can be instrumental in shifting the default mode from distracted mind-wandering (what some term the “doing” mode of mind) to one of mindful awareness (the “being mode” of mind).6 Moreover, with deepening practice, mindfulness training might play a role in fostering a shift from a transitory state to a more enduring and robust trait, a way of being grounded in present-moment embodied experience rather than being caught in an elaborate cognitive self-narrative characteristic of depressive rumination, chronic anxiety, daydreaming, and self-absorbed fantasizing.
Building on this finding, a subsequent study examined the impact of Mindfulness-Based Stress Reduction (MBSR) training on the processing of “negative affect.”7 The study used a paradigm that induced negative affect by provoking sadness. Once again, this affective shift was found to recruit widespread networks known to be involved in self-referential processing. The group trained in MBSR showed a diminished neural response in the narrative focus network and augmented activity in the experiential focus network compared to the wait-list control group. Despite equivalent levels of self-reported sadness, the MBSR participants showed greater activation of the lateral neural circuits associated with experiential focus—those associated with visceral and somatosensory processes and the perception of bodily sensations. The recruitment of these neural regions was associated with decreased depression scores among the MBSR participants.
These findings suggest pathways through which mindfulness training may beneficially influence the processing of negative emotion and alter the neural circuitry through which sadness itself is experienced. Novices who experienced temporary sad moods activated the narrative focus network: brain areas that treated their sadness as a problem to be analyzed and solved. People trained in MBSR, on the other hand, activated the experiential focus network: brain areas that provided feedback about what sadness felt like in the body. At the level of conscious experience, practicing mindfulness seems to allow individuals to see that it is possible to take a wholly different approach to the endless cycles of mental strategizing and affliction that are part and parcel of depression and anxiety.
A major new area of interest that has emerged in recent years involves the question of whether systematic training in meditation may be associated with actual structural changes in the brain. Basic research on neuroplasticity certainly suggests the possibility of structural changes in response to mental training. However, it is only in the past several years that a sufficient body of evidence has accumulated to strongly suggest that such changes do in fact occur. In a recent randomized trial, Sara Lazar and her colleagues demonstrated increases in gray matter density in several brain regions critical for learning, memory, and emotion regulation, including the hippocampus and posterior cingulate, following MBSR training.8 Another related study from Lazar’s group linked reductions in self-reported perceived stress produced by MBSR to decreases in gray matter density in the right basolateral amygdala.9 This is the first report of structural changes in the amygdala following MBSR training. Future research may determine the extent to which other affective changes reported with MBSR might be associated with changes in the size of the amygdala.
Alterations in Autonomic, Immune, and Endocrine Function
The effects of meditation on the autonomic nervous system are likely to be complex and to vary with the type of meditation practice. In 2006, two studies investigated the impact of body scan–based meditation practices derived from MBSR on a range of autonomic functions.10 The first study compared a group using the body scan meditation as taught in MBSR to a group using progressive muscle relaxation and a wait-list control. The second study compared effects of the body scan meditation practice to a control condition in which the same participants listened to a popular novel on audiotape. In both studies, during the body scan meditation, participants showed significantly higher respiratory sinus arrhythmia, an index that reflects effects on cardiac control by the parasympathetic nervous system (sometimes known as “rest and digest,” in contrast to the fight-or-flight functions of the sympathetic nervous system). In the second study only, a marker sensitive to sympathetic nervous system influence on the heart was measured. Interestingly, this study found a significant increase in sympathetic nervous system influence on the heart with meditation compared with the control condition. Collectively, the findings from this report suggest increases in both parasympathetic and sympathetic cardiac activity during the body scan meditation practice among novice practitioners. This is a particularly interesting and important finding since the parasympathetic nervous system and sympathetic nervous system are usually inversely related but mindfulness meditation appeared to activate both branches of the autonomic nervous system simultaneously.
A recent report from the Shamatha Project measured telomerase activity following a three-month retreat emphasizing shamatha practice compared with a wait-list control group.11 Telomeres are repeated DNA sequences at the end of the chromosomes that protect critical genetic information within the chromosome from being damaged, and telomerase is the enzyme that extends and/or restores these sequences at the ends of chromosomes. Telomerase activity is of major interest because lower levels, along with reductions in telomere length, have been linked to accelerated rates of biological aging in the face of unremitting stress.12 At the end of the retreat, telomerase activity was significantly greater among the shamatha practitioners compared to the controls. The researchers also reported observing complex relationships between changes on a number of self-reported personality dimensions (such as neuroticism) and telomerase activity between groups. Those retreat practitioners who showed the greatest increases in perceived control and greater decreases in neuroticism after the retreat showed the largest increases in telomerase activity.
Among the significant developments since the 2005 meeting has been the continued investigation and spread of mindfulness-based cognitive therapy (MBCT), an intervention modeled on MBSR. This intervention is now recommended by the National Health Service in the United Kingdom for people with a history of three or more episodes of major depressive disorder.13 MBCT, which was designed to help recovered but recurrently depressed patients develop mindfulness strategies for relating differently to patterns of thinking that induce depression, significantly decreases the risk of relapse and recurrence.14 MBCT emphasizes daily practice of formal and informal mindfulness meditation practices, including mindful yoga. These practices may also serve as ideal constituents of an ongoing maintenance strategy, particularly in regard to depressive rumination.
In an important new study, Zindel Segal and his colleagues tested eighty-four patients with a diagnosis of major depressive disorder who were currently in remission following treatment with an antidepressant medication.15 These patients were randomly assigned to one of three conditions: discontinuing the antidepressants and attending eight weekly group sessions of MBCT; continuing with their therapeutic dose of antidepressant; or discontinuing active medication and being transitioned onto placebo. The main outcome measure was relapse into a depressive episode. The findings revealed that MBCT and continued medication were equivalent in protecting against relapse compared with placebo. Thus, the study importantly showed that MBCT can be considered a medically equivalent alternative to medication for patients at risk for major depressive relapse who do not wish to continue on antidepressants.
Another study recently examined the impact of MBSR on emotion regulation in patients with social anxiety disorder.16 It found that MBSR led to improvements in symptoms of anxiety and depression, and in self-esteem in a small group of these patients. Following the MBSR intervention, participants were monitored during a task probing negative self-beliefs while they were also engaging in either a breath-focused attention task or a distraction task. Functional magnetic resonance imaging showed decreased negative emotional experience and decreased activation in the amygdala during the breath-focused task.
Variants of MBSR have been developed to specifically address substance abuse and craving. Mindfulness-based relapse prevention (MBRP) is the most well-developed intervention of this sort.17 In the most comprehensive study of MBRP for patients with substance use disorder, 168 patients were randomly assigned to either MBRP or treatment as usual, which consisted of counseling and educational information.18 Among patients receiving treatment as usual, the experience of craving was associated with both depressive symptoms and substance use. However, MBRP significantly changed the relationship between craving and depression so that when feelings of craving arose, they no longer automatically triggered depression, and these changes predicted reduced substance use four months after the intervention. These findings indicate that while MBRP does not directly affect substance use, it does decrease the link between craving and depression, and this in turn may affect subsequent substance use. Clearly, additional research is required to tease apart these complex effects and to determine whether preexisting individual differences are associated with differential response to interventions such as MBRP. A recent study indicated that brief mindfulness training for cigarette smokers resulted in greater reductions in cigarette use following a four-week mindfulness-based treatment and at a seventeen-week follow-up compared to individuals randomized to an American Lung Association Freedom from Smoking treatment. Mindfulness was shown to directly reduce craving itself in this study.19
As several recent comprehensive reviews of selective segments of the scientific literature on the impact of meditation reveal, the methodological shortcomings of the extant research are considerable. For example, a major 2007 report on the health effects of meditation commissioned by the National Center for Complementary and Alternative Medicine reached the following conclusion: “Scientific research on meditation practices does not appear to have a common theoretical perspective and is characterized by poor methodological quality. Firm conclusions on the effects of meditation practices in healthcare cannot be drawn based on the available evidence. Future research on meditation practices must be more rigorous in the design and execution of studies and in the analysis and reporting of results.”20
There are numerous critical methodological issues germane to the scientific study of clinical interventions, particularly psychological interventions, but here we focus on a few that are unique to research on meditation. One of the most critical is the choice of control groups for intervention studies. For example, what would be a proper control group for MBSR? This question is becoming increasingly relevant. It is clear that a wait-list control design, while a perfectly appropriate choice for earlier studies, is now no longer sufficient, since there are many features of MBSR interventions that are not specific to the meditation practices themselves but might contribute to changes in standard outcome measures. Comparison conditions that match the MBSR condition for variables such as group process, enthusiasm of the instructor, belief that the intervention will produce beneficial change, length of home practice, and so on are necessary to conclusively establish that the meditation practices per se are responsible for the measured outcomes.
Other critical methodological issues concern measurement of practice time and assessment of past meditation experience. For the latter, the field critically needs a formal structured interview for use with different meditation traditions that would yield reliable measures of past practice. Measuring practice time within a study is somewhat more complicated since there are many opportunities for informal practice that might not get incorporated into people’s reports of their practice time. Also, it has not been established that individuals report practice time reliably. While we are not suggesting that people would consciously dissimulate about their practice time, it is well-known that many individuals show a propensity to present themselves in a positive light, and many of the meditation studies inevitably create an expectation that good subjects are those who practice as much as they are told to practice.
Of particular importance for studies of meditation practices that emphasize mindfulness is a behavioral measure of mindfulness. Self-report measures have uncertain validity. Moreover, individuals’ ability to report on their internal experience may not be well developed, particularly in the early stages of meditation practice. Thus, self-report questionnaires may reflect a person’s internal biases about the kinds of experiences “a mindful person” is supposed to have, rather than being a veridical report of actual interior experience. This is an area of vigorous debate and investigation at present.21 A well-validated behavioral measure that takes these important issues into account would enable investigators to more systematically examine individual differences by determining if participants who show greater increases in the behavioral measure of mindfulness also show more improvements in the other outcome measures being assessed. This would place the field on a considerably firmer footing than it now occupies, since virtually all analytic efforts to characterize individual differences in mindfulness to date have relied on such self-report measures.
Prospects for the Future
On the clinical side, we are beginning to better understand relations between the central circuitry of emotion and peripheral biology that may be relevant to health and to specific illnesses.22 This growing knowledge provides a foundation for examining and understanding how different forms of meditation may influence the central circuitry of emotion and, in turn, have downstream consequences that are relevant to specific health outcomes. If a physical disorder can be influenced to one degree or another by psychosocial factors, we would expect that the brain would be involved in modulating the peripheral organ systems implicated in the disease, allowing for the possible influence on disease-relevant biology via modulation of central neural circuits through meditation.
At the level of whole populations, research is critically needed to evaluate the impact of meditation on health care utilization. While there are anecdotal descriptions of decreased health care utilization among meditation practitioners, no rigorous studies have examined this issue. This kind of effort should ideally be guided by a health care economist and be conducted at multiple sites. If meditation is found to reduce health care utilization even by a few percentage points, it would have enormous economic consequences for health care, nationally and globally. This kind of information would provide a powerful incentive for government and insurance agencies to take meditative practices more seriously at the public health level. We hope that a well-designed and rigorous study of the effects of a meditation-based intervention on health care utilization will be undertaken as soon as possible.
While there have been a number of recent reports on the application of meditation in children, the literature is spotty, the interventions extremely varied, and the outcomes poorly measured.23 However, the potential for intervention early in life to have a beneficial impact on specific conditions is high, given that neuroplasticity is likely to be greater, particularly during the preadolescent period. [M]ethods of mental training that might help cultivate greater equanimity, emotional balance, and discernment prior to entering the adolescent risk period are critical, and might be potentially lifesaving. An appreciation of impermanence and not taking personally what is not personal are certainly critical elements of mindfulness training that might greatly benefit children and adolescents.
In terms of basic research, two major methodological and conceptual advances are likely to have dramatic impacts on the kinds of questions that can be asked about the impact of meditation practice in the future. One is epigenetics, the study of the factors that regulate gene expression. It has now been definitively established that environmental factors can regulate gene expression.24 This raises the possibility that mental training can also regulate gene expression, though as yet no rigorous published studies have addressed this issue. There is preliminary evidence that relaxation procedures produce alterations in gene expression, though systematic comparisons with rigorous control groups have not yet been reported.25
The other major methodological and conceptual advance concerns the human connectome—the project to map the functional and structural connections of the human brain.26 Methods are now available to characterize structural and functional connections between each volume element (that is, the three-dimension pixel known as a voxel) and every other voxel in the human brain. Such rich information might contain sufficient sensitivity to better characterize the impact of different forms of meditation on neural circuits.
Ultimately, the ongoing development and deployment of mindful awareness and the cultivation of positive emotions, including kindness toward oneself, may well be shown to serve both literally and metaphorically as the mind’s own physician, a powerful resource available to all who care to listen deeply to the currents of one’s own mind, heart, body, and life. The science is already suggesting on the whole that this may be so, even as, perhaps more importantly, we note the experiences of countless meditation practitioners, who seem to be benefiting in terms of quality of life, health, and well-being from this emerging perspective on the value and practicality of the meditative disciplines.
Reprinted from The Mind's Own Physician with permission: New Harbinger Publications, Inc., Copyright © 2012 Jon Kabat-Zinn and Richard J. Davidson with Zara Houshmand.
1. H. A. Slagter, A. Lutz, L. L. Greischar, et al., “Mental Training Affects Distribution of Limited Brain Resources,” Public Library of Science Biology 5, no. 6 (2007): e138.
2. K. A. MacLean, E. Ferrer, S. R. Aichele, et al., “Intensive Meditation Training Improves Perceptual Discrimination and Sustained Attention,” Psychological Science 21, no. 6 (2010): 829–839.
3. F. Zeidan, S. K. Johnson, B. J. Diamond, et al., “Mindfulness Meditation Improves Cognition: Evidence of Brief Mental Training,” Consciousness and Cognition 19, no. 2 (2010): 597–605.
4.A. Wallace, The Attention Revolution: Unlocking the Power of the Focused Mind (Boston: Wisdom Publications, 2006).
5. M. Kozhevnikov, O. Louchakova, Z. Josipovic, et al., “The Enhancement of Visuospatial Processing Efficiency through Buddhist Deity Meditation,” Psychological Science 20, no. 5 (2009): 645–653.
6. J. M. G. Williams, “Mindfulness, Depression, and Modes of Mind,” Cognitive Therapy and Research 32, no. 6 (2008): 721–733; J. Kabat-Zinn, Full Catastrophe Living (New York: Dell, 1990), 96–97; and J. Kabat-Zinn, Wherever You Go, There You Are (New York: Hyperion, 1994), 14.
7. N. A. Farb, A. K. Anderson, H. Mayberg, et al., “Minding One’s Emotions: Mindfulness Training Alters the Neural Expression of Sadness,” Emotion 10, no. 1 (2010): 25–33.
8. B. K. Hölzel, J. Carmody, M. Vangel, et al., “Mindfulness Practice Leads to Increases in Regional Brain Gray Matter Density,” Psychiatry Research 191, no. 1 (2011): 36–43.
9. B. K. Hölzel, J. Carmody, K. C. Evans, et al., “Stress Reduction Correlates with Structural Changes in the Amygdala,” Social Cognitive and Affective Neuroscience 5, no. 1 (2010): 11–17.
10. B. Ditto, M. Eclache, and N. Goldman, “Short-Term Autonomic and Cardiovascular Effects of Mindfulness Body Scan Meditation,” Annals of Behavioral Medicine 32, no. 3 (2006): 227–234.
11. T. L. Jacobs, E. S. Epel, J. Lin, et al., “Intensive Meditation Training, Immune Cell Telomerase Activity, and Psychological Mediators,” Psychoneuroendocrinology 36, no. 5 (2010): 664–681.
12. E. S. Epel, E. H. Blackburn, J. Lin, et al., “Accelerated Telomere Shortening in Response to Life Stress,” Proceedings of the National Academy of Sciences 101, no. 49 (2004): 17312–17315.
13. National Institute for Clinical Excellence, Depression: Management of Depression in Primary and Secondary Care, National Clinical Practice Guidelines, no. 23 (London: HMSO, 2004; updated 2009).
14. J. D. Teasdale, Z. V. Segal, J. M. G. Williams, et al., “Prevention of Relapse/Recurrence in Major Depression by Mindfulness-Based Cognitive Therapy,” Journal of Consulting and Clinical Psychology 68, no. 4 (2000): 615–623; and Z. V. Segal, J. M. G. Williams, and J. D. Teasdale, Mindfulness-Based Cognitive Therapy for Depression: A New Approach to Preventing Relapse (New York: Guilford Press, 2002).
15. Z. V. Segal, P. Bieling, T. Young, et al., “Antidepressant Monotherapy vs. Sequential Pharmacotherapy and Mindfulness-Based Cognitive Therapy, or Placebo, for Relapse Prophylaxis in Recurrent Depression,” Archives of General Psychiatry 67, no. 12 (2010): 1256–1264.
16. P. R. Goldin and J. J. Gross, “Effects of Mindfulness-Based Stress Reduction (MBSR) on Emotion Regulation in Social Anxiety Disorder,” Emotion 10, no. 1 (2010): 83–91.
17. S. Bowen, N. Chawla, S. E. Collins, et al., “Mindfulness-Based Relapse Prevention for Substance Use Disorders: A Pilot Efficacy Trial,” Substance Abuse 30, no. 4 (2009): 295–305.
18. K. Witkiewitz and S. Bowen, “Depression, Craving, and Substance Use Following a Randomized Trial of Mindfulness-Based Relapse Prevention,” Journal of Consulting and Clinical Psychology 78, no. 3 (2010): 362–374.
19. J. A. Brewer, S. Mallik, T. A. Babuscio, et al., “Mindfulness Training for Smoking Cessation: Results from a Randomized Controlled Trial,” Drug and Alcohol Dependence (June 30, 2011): epub ahead of print.
20. M. B. Ospina, T. K. Bond, M. Karkhaneh, et al., Meditation Practices for Health: State of the Research, Evidence Report/Technology Assessment 155 (Rockville, MD: Agency for Healthcare Research and Quality, 2007), v.
21. See P. Grossman and N. T. Van Dam, “Mindfulness, by Any Other Name . . . : Trials and Tribulations of Satî in Western Psychology and Science,” Contemporary Buddhism 12, no. 1 (2011): 219–240; and R. A. Baer, “Measuring Mindfulness,” Contemporary Buddhism 12, no. 1 (2011): 241–262.
22. See, for example, M. A. Rosenkranz, W. W. Busse, T. Johnstone, et al., “Neural Circuitry Underlying the Interaction between Emotion and Asthma Symptom Exacerbation,” Proceedings of the National Academy of Sciences 102, no. 37 (2005): 13319–13324.
23. D. S. Black, J. Milam, and S. Sussman, “Sitting-Meditation Interventions among Youth: A Review of Treatment Efficacy,” Pediatrics 124, no. 3 (2009): e532–541.
24. T. Y. Zhang and M. J. Meaney, “Epigenetics and the Environmental Regulation of the Genome and Its Function,” Annual Review of Psychology 6 (2010): 439–466.
25. J. A. Dusek, H. H. Out, A. L. Wohlhueter, et al., “Genomic Counter-Stress Changes Induced by the Relaxation Response,” Public Library of Science One 3, no. 7 (2008): e2576.
26. O. Sporns, G. Tononi, and R. Kötter, “The Human Connectome: A Structural Description of the Human Brain,” Public Library of Science Computational Biology 1, no. 4 (2005): e42.